A well can include a borehole (or “wellbore”) that is drilled into the earth. A well can provide access to a subsurface formation (a geographic formation below the earth's surface) to facilitate the extraction of natural resources, such as hydrocarbons and water from the subsurface formation, to facilitate the injection of fluids into the subsurface formation, and to facilitate the evaluation and monitoring of the subsurface formation. In the petroleum industry, wells are often drilled to extract (or “produce”) hydrocarbons, such as oil and gas, from subsurface formations. The term “oil well” is often used to describe a well designed to produce oil. In the case of an oil well, some natural gas is typically produced along with oil. Wells producing both oil and natural gas are sometimes referred to as “oil and gas wells” or “oil wells.” The term “gas well” is normally reserved to describe a well designed to produce primarily natural gas.
Creating an oil well typically involves several stages, including a drilling stage, a completion stage and a production stage. The drilling stage typically involves drilling a wellbore into a subsurface formation that is expected to contain a concentration of hydrocarbons that can be produced. The portion of the formation expected to contain hydrocarbons is often referred to as a “hydrocarbon reservoir” or a “reservoir.” The drilling process is often facilitated by a vertical drilling rig that sits at the earth's surface. The drilling rig provides for operating the drill bit; hoisting, lowering and turning drill pipe and tools; circulating drilling fluids; and generally controlling down-hole operations (operations in the wellbore). The completion stage involves making the well ready to produce hydrocarbons. In some instances, the completion stage includes pumping fluids into the well to fracture, clean or otherwise prepare the reservoir to produce the hydrocarbons. The production stage involves producing (extracting and capturing) hydrocarbons from the reservoir by way of the well. During the production stage, the drilling rig is normally removed and replaced with a collection of valves, often referred to as a “production tree” or a “Christmas tree”, that regulates pressure in the wellbore, controls production flow from the wellbore, and provides access to the wellbore in the case further completion work is needed. A pump jack or other mechanism can provide lift that assists in extracting hydrocarbons from the reservoir, especially in instances where the pressure in the well is so low that the hydrocarbons do not flow freely to the surface. Flow from an outlet valve of the production tree is often coupled to a distribution network, such as tanks, pipelines and transport vehicles that supply the production to refineries, export terminals, and so forth.
A well traditionally includes a generally vertical wellbore that extends downward into the earth, in a direction that is generally perpendicular to the earth's surface. Such a well is often referred to as a “vertical well”. The term “horizontal well” is often used to describe a well having a wellbore section that extends in a generally horizontal direction. A horizontal well often includes a generally vertical or deviated wellbore having an upper-vertical wellbore portion that extends downward into the earth in a direction that is generally perpendicular to the earth's surface, and a lower-horizontal wellbore portion that extends in a generally horizontal direction through the earth, often following a profile of a reservoir. In either case, a vertical drilling rig is normally positioned at the earth's surface, above the location of the wellbore, and provides for lowering and raising drill pipe, tools, and the like vertically, into and out of the wellbore.